1. Field of the Invention
The invention relates to an autonomous and self-propelled vehicle comprising feed-displacement means for laterally displacing feed.
2. Description of the Related Art
Such a vehicle is known from WO 2009/070007 A1, hereby incorporated by reference in its entirety. This vehicle comprises a frame to which feed-displacement means are fitted in the form of a freely rotating circular element, the outer periphery of which forms the outer periphery of the unmanned vehicle. The freely rotating element is driven by frictional contact with the feed and/or pressure of the feed. As a result of the rotation of the element, the feed is displaced laterally with respect to the direction of travel of the vehicle. This vehicle is used in animal housing units in which, for example, cows can reach the feed on the ground through a wall in order to eat. The vehicle then ensures that the feed comes to lie near the wall and remains within reach of the cows.
WO 2009/070007 A1 discloses one diagrammatic embodiment of the freely rotating circular element. FIG. 1 of WO 2009/070007 shows a freely rotating element which has a shape and a vertical axis which is rendered as a dash-dotted line without a reference numeral, in which the end faces of the shape are not perpendicular to the axis. The illustrated embodiment is not able to work properly in practice.
Rotation of the element can be effected in two ways. The element can be rotated in its entirety about the axis, in which case the orientation of the element co-rotates. This means that the lowest point co-rotates, and may, for example, also come to lie on the rear side of the vehicle. However, this is not desirable as such a changing orientation makes it likely that feed may come to lie under the vehicle during a large part of the rotation, due to the difference in height.
In another rotation option, the element is rotated about the cylinder axis, in which case the orientation of the element, i.e. the position of the lowest point, as shown in FIG. 1 of WO 2009/070007 A1, does not change. A drawback thereof is that the freely rotating element is twisted upon rotation about the cylinder axis. In order to allow this twisting movement without a relatively high resistance, the freely rotating element will have to be designed to be flexible, which has an adverse effect on the pushing function and thus on the feed-displacing function of the element.
In addition, two vehicles are known in which the feed-displacement means are conical, with the cone shapes tapering either towards the top or towards the bottom. A drawback of the upwardly tapering feed-displacement means is that when they are driven by friction with the ground, a relatively large amount of resistance is produced when the vehicle takes bends. A drawback of the downwardly tapering feed-displacement means is that the wheel base and thus the stability of the vehicle is limited.